The Lombardi Cancer research Center proposes to participate in the colectal clinican trials of the Gastrointestinal Tumor Study Group, with emphasis on the development of new treatment strategies for the surgical adjuvant setting. The use of adjunctive hepatic radiation with 5-fluorouracil for Dukes C1 and C2 colon cancer will be evaluated in an attempt to reduce the expected high incidence of hepatic recurrence as well as controlling other sites of systemic metastasis. For rectal cancer, the use of postoperative radiation therapy with chemotherapy has been demonstrated to result in a significant reduction in recurrence. Working with the Gastrointestinal Tumor Study Group, we will now attempt to determin whether the same significant improvement in relapse-free survival can be maintained while reducing the toxicity of the combined modality regimen; radiation therapy with 5-fluorouracil and methyl-CCNU chemotherapy will be compared with the use of pelvic irradiation with only two courses of 5-fluorouracil in a control Phase III trial. New chemotherapeutic regimens for the management of advanced colorectal cancer will be designed and evaluated in Phase II or Phase III trials, in cooperation with other members of the Group. The overal intent is to increase the survival rate for patients who have come to curative resection but nevertheless remain at a high statistical probability for relapse, and to provide better palliative therapy for the patient with advanced metastatic disease.